The major portion of our present knowledge of cerebellar function has been gained from experiments on anesthetized or decerebrate animals using electrical stimulation. Such an approach must be considered at best, a first approximation of how the system is organized to function. These experiments do not deal directly with the animals motor behavior. The purpose of these experiments is to investigate the role that individual cerebellar cells play in guiding efficient finely coordinated motor behavior in the unanesthetized and unrestrained cat. The experiments involve normal walking and running behavior of cats while cerebellar Purkinje cell activity and the EMG is monitored by telemetry. Forepaw hitting and striking behavior of the cat are also under investigation. Thus cerebellar neuronal activity will be investigated during two basically different motor tasks. The first (walking) is dependent upon feedback from peripheral muscle or joint receptors whereas the second (striking) operates so rapidly as to exclude such a feedback mechanism. Finally, to bridge the gap with those studies that have been performed under anesthesia, the firing patterns of cerebellar neurons in the awake animals is being compared with those in the anesthetized animal.